GRA wrote:I watched it, and all through I just kept thinking, what a tremendous expenditure of human energy, brainpower and money for a meaningless stunt.

I don't agree with what was portrayed as perhaps the "main meaning" of this adventure, but I hardly see it as "a meaningless stunt".

GRA wrote:The attempted justifications to try and provide some larger context (We're popularizing sustainable energy and energy efficiency!) struck me as as at least a decade too late - If this flight had started in 2005 instead of 2015 that might have been valid, but RE and energy efficiency were both widespread and well known by the time this came about.

Bertrand Piccard conceived of this flight in 1999. No doubt he fully intended to complete this flight in, or before, 2005. I'm pretty sure he did not expect it would take 16 years and countless millions of Euros before the around-the-world flight could be started.

My family and I went to see the Solar Impulse several years back. That Solar Impulse plane that we saw at the Udvar-Hazy Museum was not this one which flew around the world, it was a prototype. In other words, that one was not quite able to achieve the final objective.

My conclusion from all of this is that this flight was not really possible before 2015. It's clear from what was portrayed in the NOVA documentary that it was barely achievable as it was. I believe that this type of "first" is important because when we look back on history, we can say with some confidence that such a feat was likely NOT possible using the technology which existed up until approximately that point in time.

Of course it wasn't possible in 2005, and as you note it was barely possible in 2015-16. The main justification for both pilots was to achieve a first, and while that's good for getting into the record books and makes the sponsors happy, it often (as in this case) has nothing to do with technical development for practical usage. Firsts/records are something that runs in Piccard's family, as both his father Jacques (first along with Don Walsh in the bathyscaphe Trieste to the bottom of the Challenger Deep of the Marianas Trench, the deepest known point in the ocean) and grandfather Auguste (set and then broke his own absolute height record, in 1931 and 1932, in balloons with two different companions) did them, and Bertrand along with Brian Jones were the first to make a non-stop balloon circumnavigation. At least in Auguste's case they were expanding scientific knowledge, and there was some minimal information gained by the Trieste. I can't say the same for this flight.

RegGuheert wrote:

GRA wrote:If you watched the show, you know that the decision to take off for Hawaii was made against the unanimous advice of the engineers, who said it wasn't worth the risk.

I did watch the show and that is NOT what happened. What ACTUALLY happened is Pierre took off for Hawaii with the full blessing of the engineering team. After some time, he reported a malfunction with the system which monitors the autopilot and alerts the pilot if it determines his attention is needed. This malfunction threatened to (and proved to) put additional stress on a pilot who was already attempting to extend a human endurance record by a large margin (over 5 days of continuous flying versus 3 days). The engineers, who have responsibility for the safety of both the pilot and the aircraft, felt that this added additional risk was not warranted and they recommended that Pierre turn around and return to Japan before he reached the limit of an abort. Pierre and Bertrand overrode their recommendation and decided to push on to Hawaii. This created a significant amount of friction within the team and Bertrand fully expected some of them to quit even if they reached Hawaii safely. NOVA did an admirable job of capturing this very human drama.

Yes, you're right about the sequence. Thanks for correcting my memory.

RegGuheert wrote:Your characterization of this decision is:

GRA wrote:That the pilot decided to do so anyway shows that this was about personal goals and not disappointing sponsors rather than gathering technical information, not that there was ever much doubt about that.

You went on to imply that this had become a "daredevil stunt". I have to agree with you that achieving the goal of flying this plane around the world was very much at the forefront of the decision to push on, but while it was originally a personal goal of only Bertrand Piccard, it had also become a corporate goal of ALL of the people involved in the effort as well as of the financial sponsors and many other supporters.

What you failed to point out were the following very pertinent facts:- Pierre had previously aborted this flight after taking off due to adverse weather conditions, resulting in the plane being in Japan instead of China.- The flight had been aborted again on the runway while trying to take off from Japan, again based on weather.- As a result of these two aborts, the window was rapidly closing on successfully achieving this five-plus-day flight to Hawaii. The main reasons for this were 1) the Summer solstice had passed and thus the available solar energy for the flight was being reduced each day. There was very little energy margin, even right at the solstice, 2) The typhoon season was quickly approaching, which not only threatened to prevent the flight, but could actually destroy the blow-up hangar and the plane itself, and 3) The team was starting to suffer from severe fatigue from the waiting and the three periods of intense preparation (and worrying) for this most-difficult flight which they had just gone through.- Bertrand felt that if this flight was aborted, the entire mission would fail.

So did they make the wrong decision? Hindsight tells us that the flight to Hawaii was a success. Pierre was certainly more harassed by the autopilot monitor than he should have been, but he did an amazing job piloting the plane and pulled through to achieve an incredible world-record feat of endurance. The batteries failed during that flight and the rest of the mission had to be pushed back until 2016, but that design issue was already baked in and was not part of the go/no go decision. And, yes, the engineers were pissed off that their recommendation had been overruled by "two managers". In the end, however, none of them quit.

I have to say I feel that Bertrand and Pierre made the correct decision. Note that those two people who made that decision were the person whose life was on the line and the person whose personal reputation was most on the line. They personally had the most to lose in case of a failure. Ultimately, the entire team would have been MUCH more upset had they aborted and had the entire mission been scrubbed.

All of which just goes to show that personal and PR motivations drove this, not technical development. Sure, Piccard and Pierre chose to risk their lives, but as there's absolutely no need to do so in this case to gather technical data, it's clear that the driving force was personal (ego if you will) rather than scientific. Nothing wrong with that, as lots of people try and test their own limits, but it's not science. There were a couple of moments in the film that I thought accurately showed the adventurer/explorer as hero idea. One was when Piccard was having stomach problems and wanted to take off anyway, Pierre took him aside and out of hearing I imagine told him not to be an idiot - aside from every other reason not to do this, the last thing you want when flying in an unpressurized a/c over 25kft is gastric issues.

The other case was when Bertrand gave an example of Chuck Yeager choosing to fly the Mach 1 flight with a broken rib as a reason to press on, which is a perfect example of personal goals overriding sound decisions (and was immediately quashed by the Chief Engineer IIRR). If Yeager hadn't made the flight his back-up Bob Hoover would have, or they could have waited until Yeager was able to fly - there was no technical reason to rush. As it happens it's entirely possible that the sound barrier had been broken by George Welch in a dive in the prototype P-86 (later F-86) Sabre shortly before, but as it wasn't instrumented to the same level there was no way to tell - the F-86 was definitely capable of doing it. Yeager did the flight because he wanted to be first, plus the usual fighter pilot "I can hack it" machismo. But if the flight had failed because of his injury, with the loss of the a/c and/or his life, would anyone conclude that he made a good decision?

RegGuheert wrote:As far as collecting data goes, the data which was yet to be collected was the data which could ONLY be gathered on this leg of the mission. They needed to find out if the plane could store enough potential and battery energy to make it through the night over the Pacific, and to do this over and over again each day for five days. They also needed to find out if Pierre could manage to fly the plane for five days. The ONLY way to collect that data was to actually DO it. It turned out that Pierre WAS able to succeed even with an additional hurdle put in his way. OTOH, it also turned out that the thermal design of the batteries was insufficient for the purpose.

Data could just have easily been collected flying over land, or out and back over the ocean. It was the need to be seen as the adventurer as hero that made it necessary to fly over the Pacific. After all, can you name the pilots who prior to Lindbergh flying non-stop to Paris had previously flown a non-stop distance and endurance more than sufficient to make the flight ( in the a/c Lindbergh had tried to buy for the fligh)t, but did so while flying back and forth over Long Island? I mentioned them in my post a page or two back, but I'll repeat their names: Clarence Chamberlain and Bert Acosta. How about the names of the first pilots to fly across the U.S. non-stop (in 1924), a greater distance than that from Newfoundland to Ireland? Or how about the names of the designers of the WB-2 and the Spirit of St. Louis; can you tell me either without checking the wiki? The main reason why flying across a large body of water engages the public's mind is because of the perceived (and in many cases actual) greater danger to humans, and their willingness to risk it. Can you name the first trans-oceanic flight by a drone, without looking it up?

RegGuheert wrote:Ultimately, it was bad enough that this around-the-world series of flights stretched into a second year. In my mind, that was a bit of a failure. But had they balked at attempting that longest leg in 2015, the effort possibly would have either dissolved at that point or the adventure would have stretched into the third year, with no improvement in the possibility of success, but a greatly increased probability of failure due to a loss of funding.

RegGuheert wrote:I appreciated that NOVA did an excellent job of showing how challenging this task really was. I appreciate this documentary in the same way that I appreciate the HBO documentary series "From the Earth to the Moon" that brought that same kind of information to light about the Mercury, Gemini, and Apollo missions. Ultimately, there are a LOT more challenges in such an undertaking than you can appreciate by just watching it unfold on TV or on the internet. The difference with the NOVA documentary is that they recorded the events as they happened, so likely it was more accurate than the HBO dramatizations.

Much as I watched the flights, the whole manned moon program was largely an exercise in the astronaut as mythic hero - the public had far less interest in the 20 or so previous unmanned flights which had reached the moon and orbited, crashed into or landed on it, and which did the science. While lots of people watched Spirit and Opportunity rovers on Mars, is there any doubt that public interest will be far greater when we send humans there?

Last edited by GRA on Mon Feb 05, 2018 8:52 pm, edited 1 time in total.

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.

RegGuheert wrote:As far as collecting data goes, the data which was yet to be collected was the data which could ONLY be gathered on this leg of the mission. They needed to find out if the plane could store enough potential and battery energy to make it through the night over the Pacific, and to do this over and over again each day for five days. They also needed to find out if Pierre could manage to fly the plane for five days. The ONLY way to collect that data was to actually DO it. It turned out that Pierre WAS able to succeed even with an additional hurdle put in his way. OTOH, it also turned out that the thermal design of the batteries was insufficient for the purpose.

Data could just have easily been collected flying over land, or out and back over the ocean.

Sure, "data" could have been collected in that way, it just would not have been useful to improve the chances of a success over that leg of the flight. Here's why:

- The Solar Impulse 2 was solar-powered which has a very low airspeed and did not have sufficient energy storage in the battery to fly through a 12-hour night at the equator at a constant altitude. So how did it manage to fly halfway across the Pacific Ocean, then? They did two things that made that flight possible: 1) They stored some of the energy needed for flying overnight as potential energy rather than in the batteries, and 2) They flew from West to East, thus shortening the duration of nighttime by about 25 minutes. Part of this shortening was the direct result of the tailwinds that occur when traveling in that direction and part of it was due to the direction of rotation of the Earth. While 1) could be done anywhere, 2) required flying about 65 degrees around the globe in the direction from West to East over five or more 24-hour days.

As such, flying "out and back over the ocean" likely would have simply been impossible because of these constraints. Imagine flying "out" "over the ocean" in an easterly direction through an entire night. How would you get "back"? First of all, flying in a westerly direction is not even possible above a certain windspeed. And unless the windspeed is less than 1/3 of the airspeed of the Solar Impulse 2, then it will not be possible to get back to land before the next night. Perhaps very still conditions exist sometimes around the solstice in the equatorial Pacific or Atlantic, but it is likely rare given that is when the sun has the most impact on winds over the equator.

- Flying over land provides a strong incentive to abort while flying over water provides a strong incentive to press on. Sure, they possibly could have tried to fly for five days in an easterly direction over Asia, but, guess what?, they likely would have aborted as soon as there was the problem occurred. Why? Because it is so easy to do. And if that problem hadn't aborted the flight something else likely would have. There is nothing like the INABILITY to abort that keeps long-duration missions going.

- Because of the low solar margins, the period of time during which the flight between Japan and Hawaii is possible is a couple-month window centered around the Summer solstice. It makes no sense to use that time continuing to test the platform when they could simply make the actual flight instead.

- Finally, no amount of collecting flight data would have solved the biggest problem that they faced on that leg of the trip: the inability to predict the weather five days in advance. Only by having a plane with a higher windspeed could they have resolved that problem. That could push such a flight a decade or more into the future. Simply put, the weather is one risk which simply could not be retired for that leg of the flight.

In the end, they did the best thing they could have done: they pressed on and achieved what the the Solar Impulse 2 was designed to accomplish.

RegGuheert wrote:As far as collecting data goes, the data which was yet to be collected was the data which could ONLY be gathered on this leg of the mission. They needed to find out if the plane could store enough potential and battery energy to make it through the night over the Pacific, and to do this over and over again each day for five days. They also needed to find out if Pierre could manage to fly the plane for five days. The ONLY way to collect that data was to actually DO it. It turned out that Pierre WAS able to succeed even with an additional hurdle put in his way. OTOH, it also turned out that the thermal design of the batteries was insufficient for the purpose.

Data could just have easily been collected flying over land, or out and back over the ocean.

Sure, "data" could have been collected in that way, it just would not have been useful to improve the chances of a success over that leg of the flight. Here's why:

- The Solar Impulse 2 was solar-powered which has a very low airspeed and did not have sufficient energy storage in the battery to fly through a 12-hour night at the equator at a constant altitude. So how did it manage to fly halfway across the Pacific Ocean, then? They did two things that made that flight possible: 1) They stored some of the energy needed for flying overnight as potential energy rather than in the batteries, and 2) They flew from West to East, thus shortening the duration of nighttime by about 25 minutes. Part of this shortening was the direct result of the tailwinds that occur when traveling in that direction and part of it was due to the direction of rotation of the Earth. While 1) could be done anywhere, 2) required flying about 65 degrees around the globe in the direction from West to East over five or more 24-hour days.

As such, flying "out and back over the ocean" likely would have simply been impossible because of these constraints. Imagine flying "out" "over the ocean" in an easterly direction through an entire night. How would you get "back"? First of all, flying in a westerly direction is not even possible above a certain windspeed. And unless the windspeed is less than 1/3 of the airspeed of the Solar Impulse 2, then it will not be possible to get back to land before the next night. Perhaps very still conditions exist sometimes around the solstice in the equatorial Pacific or Atlantic, but it is likely rare given that is when the sun has the most impact on winds over the equator.

- Flying over land provides a strong incentive to abort while flying over water provides a strong incentive to press on. Sure, they possibly could have tried to fly for five days in an easterly direction over Asia, but, guess what?, they likely would have aborted as soon as there was the problem occurred. Why? Because it is so easy to do. And if that problem hadn't aborted the flight something else likely would have. There is nothing like the INABILITY to abort that keeps long-duration missions going.

- Because of the low solar margins, the period of time during which the flight between Japan and Hawaii is possible is a couple-month window centered around the Summer solstice. It makes no sense to use that time continuing to test the platform when they could simply make the actual flight instead.

- Finally, no amount of collecting flight data would have solved the biggest problem that they faced on that leg of the trip: the inability to predict the weather five days in advance. Only by having a plane with a higher windspeed could they have resolved that problem. That could push such a flight a decade or more into the future. Simply put, the weather is one risk which simply could not be retired for that leg of the flight.

In the end, they did the best thing they could have done: they pressed on and achieved what the the Solar Impulse 2 was designed to accomplish.

All of the above is correct, and makes my essential point. An a/c that can only fly downwind owing to limited speed and range and with accurate multi-day forecasts of ideal weather owing to limited strength isn't much practical use. At the current stage of development, there is no chance of this being a practical means of transportation, because the a/c is simply too limited by strength, endurance and speed to develop further. All of this could be calculated on the ground.

So, what would it take to give this some sort of practical value? As I said, much higher power density of the PV cells, and much higher energy density of the battery. I doubt that much weight saving is possible from the structure, as the show mentioned that the carbon fiber was "lighter than paper" (presumably they meant lower density), so it seems unlikely that significant weight savings can be made there. Increased density of the PV and batteries, for sake of argument let's say 3x the current values, would have allowed a considerable decrease in wingspan, higher cruise speed, and an increase in strength as well as much more simplicity and flexibility in the flight plan (no need to do a cruise descent every night), eliminating the need to accurately forecast weather out 5-6 days ahead and allowing a more direct and shorter flight. We've gotten really good at 24 hour forecasts, do a pretty good job up to 72 hours, but after that the reliability goes way down.

As for flying over land providing a strong incentive to abort while flying over water doesn't, the opposite is true. Landing or parachuting into water is scarier to most people, because of the possibility of drowning or dying of hypothermia or injury long before you're found, which is why overwater record flights get a lot more attention than those over land. Even with modern satellite/GPS ELTs and real-time telemetry as this flight had, the ocean's still a very big place. While those can still be issues on land, your odds of survival are generally higher if you survive the landing, and the odds of finding somewhere safe to land instead of crash are generally better, which is why regulations required long overwater passenger a/c flights to have 3 or more engines until the 1980s. Engines had gotten so reliable by that time that twin engine a/c started to be allowed, gradually increasing the time (distance) they could be from the nearest divert airfield at single engine cruise speed (in case they lost an engine) from 60 to the current 180 or even 207 minutes.

In sum, until such time as more practical capabilities can be achieved, there's no reason beyond personal accomplishment/ego to try something like this. Despite Rutan and Yeager flying non-stop around the world in 1986, no one's rushing to build more a/c capable of doing so, because there's no practical value. If you want to talk about more useful developments that stem from a single person's dreams, we can discuss Falcon Heavy. I think I'll watch those boosters land again. And remember, Don't Panic!

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.

GRA wrote:All of the above is correct, and makes my essential point. An a/c that can only fly downwind owing to limited speed and range and with accurate multi-day forecasts of ideal weather owing to limited strength isn't much practical use. At the current stage of development, there is no chance of this being a practical means of transportation, because the a/c is simply too limited by strength, endurance and speed to develop further. All of this could be calculated on the ground.

As you know, we agree on that point:

RegGuheert on July 24, 2016 wrote:While I find that some of the flight-endurance records set were impressive, I don't feel this was a very positive demonstration of the many benefits of Solar power. Simply put, Solar-powered flight may have some interesting applications in reconnaissance or as telecommunications relays, but I doubt that it will ever make much sense for transporting people or cargo around the globe. Of course, time will tell.

GRA wrote:All of the above is correct, and makes my essential point. An a/c that can only fly downwind owing to limited speed and range and with accurate multi-day forecasts of ideal weather owing to limited strength isn't much practical use. At the current stage of development, there is no chance of this being a practical means of transportation, because the a/c is simply too limited by strength, endurance and speed to develop further. All of this could be calculated on the ground.

As you know, we agree on that point:

RegGuheert on July 24, 2016 wrote:While I find that some of the flight-endurance records set were impressive, I don't feel this was a very positive demonstration of the many benefits of Solar power. Simply put, Solar-powered flight may have some interesting applications in reconnaissance or as telecommunications relays, but I doubt that it will ever make much sense for transporting people or cargo around the globe. Of course, time will tell.

It was my understanding that we agreed that this was a poor use of PV/Solar. Where we differed, AIUI, is that you were saying that you thought it had enough other scientific benefits to give it broader value, and I don't see it as anything other than a personal accomplishment. I've always liked the title of the French mountaineer Lionel Terray's climbing autobiography: "Conquistadors of the Useless". There's an acknowledgement that he was climbing for his own reasons, for enjoyment, as a personal test and maybe some fame, with no wider meaning or value, albeit some new technical knowledge was gained. I consider this flight to fall into the same category, as I do Lindbergh's or Post's, or Rutan/Yeager's.

At least some of Terray's climbs (e.g. Annapurna) explored previously untrodden territory, and the same goes for most of the heroic age explorers. But while some people can name Franklin, Burton and/or Speke, Peary, Nansen, Amundsen or (most likely, owing to the death of his party and his diary) Scott, how many can name even a single scientist who participated in the IGY, or any of the science that they produced?

That being said, I hope a book will eventually come out which goes into far more detail about the design of both a/c, technical limitations, meteorology, physiology etc. of the flight, which is far more useful from the science perspective (which is what Nova is supposed to be) than making an in-flight phone call to Ban Ki-Moon.

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.

GRA wrote:Where we differed, AIUI, is that you were saying that you thought it had enough other scientific benefits to give it broader value, and I don't see it as anything other than a personal accomplishment.

No, I never said that. Here is what I actually said:

RegGuheert wrote:I don't agree with what was portrayed as perhaps the "main meaning" of this adventure, but I hardly see it as "a meaningless stunt".

I also said this:

RegGuheert wrote:I believe that this type of "first" is important because when we look back on history, we can say with some confidence that such a feat was likely NOT possible using the technology which existed up until approximately that point in time.

In other words, it is not about creating "scientific benefits" but rather it is about putting a stake in the ground to say "the technology of today now allows us to do this!" And this was done in a way that history has recorded the event.

But make no mistake: by working on projects that push the envelope of what is achievable, new insights are gained. To me, this is axiomatic. Trying to do something that is impossible always leads to new ideas about how something can be approached, even if it ultimately leads to failure. In my career, I spent about the same period of time as Bertrand Piccard (about 16 years) trying to do something that was impossible. In the end, I achieved success in the endeavor. Just like Bertrand Piccard, I didn't know what I didn't know and it took MUCH longer to achieve the goal than I had ever imagined. Also just like Bertrand Piccard, what was achieved was barely possible with the technology of the time. The technology I used was different technology than what I had started with, but ultimately, I was able to do something that had never been done before. Not by myself, but as part of a team with a common goal. Part of the reason it was a common goal is that I often "sold" the goal to the team as something worth pursuing.

Along the way, I pushed myself and many others to grow the technology needed to accomplish the goal. I have to say that several of the people whom I was pushing told me that they didn't mind the seemingly-endless stream of problems which I encountered and brought to them because they enjoyed difficult challenges. These challenges stretched the limits of math, computer science, and computer hardware. Later, one of those who created much of the technology that I used admitted to me that he didn't think it was possible to do what I had done. (Which is really funny because I used his math and his algorithms and his software to do it!) Many of the key components in these three areas simply did not exist when I began the journey in 1990. What was accomplished truly had been "impossible" at that time.

GRA wrote:That being said, I hope a book will eventually come out which goes into far more detail about the design of both a/c, technical limitations, meteorology, physiology etc. of the flight, which is far more useful from the science perspective (which is what Nova is supposed to be) than making an in-flight phone call to Ban Ki-Moon.

I agree that it is good to capture this type of information in books,, but I'm not as big of a book reader as you. I can certainly agree with the last part of that statement!

Ultimately, I'm glad that NOVA allowed me to "go along on the ride" with the Solar Impulse team to get a better feel for what was involved in their incredible feat.

GRA wrote:Where we differed, AIUI, is that you were saying that you thought it had enough other scientific benefits to give it broader value, and I don't see it as anything other than a personal accomplishment.

No, I never said that. Here is what I actually said:

RegGuheert wrote:I don't agree with what was portrayed as perhaps the "main meaning" of this adventure, but I hardly see it as "a meaningless stunt".

I also said this:

RegGuheert wrote:I believe that this type of "first" is important because when we look back on history, we can say with some confidence that such a feat was likely NOT possible using the technology which existed up until approximately that point in time.

In other words, it is not about creating "scientific benefits" but rather it is about putting a stake in the ground to say "the technology of today now allows us to do this!" And this was done in a way that history has recorded the event.

But make no mistake: by working on projects that push the envelope of what is achievable, new insights are gained. To me, this is axiomatic. Trying to do something that is impossible always leads to new ideas about how something can be approached, even if it ultimately leads to failure. In my career, I spent about the same period of time as Bertrand Piccard (about 16 years) trying to do something that was impossible. In the end, I achieved success in the endeavor. Just like Bertrand Piccard, I didn't know what I didn't know and it took MUCH longer to achieve the goal than I had ever imagined. Also just like Bertrand Piccard, what was achieved was barely possible with the technology of the time. The technology I used was different technology than what I had started with, but ultimately, I was able to do something that had never been done before. Not by myself, but as part of a team with a common goal. Part of the reason it was a common goal is that I often "sold" the goal to the team as something worth pursuing.

Along the way, I pushed myself and many others to grow the technology needed to accomplish the goal. I have to say that several of the people whom I was pushing told me that they didn't mind the seemingly-endless stream of problems which I encountered and brought to them because they enjoyed difficult challenges. These challenges stretched the limits of math, computer science, and computer hardware. Later, one of those who created much of the technology that I used admitted to me that he didn't think it was possible to do what I had done. (Which is really funny because I used his math and his algorithms and his software to do it!) Many of the key components in these three areas simply did not exist when I began the journey in 1990. What was accomplished truly had been "impossible" at that time.

GRA wrote:That being said, I hope a book will eventually come out which goes into far more detail about the design of both a/c, technical limitations, meteorology, physiology etc. of the flight, which is far more useful from the science perspective (which is what Nova is supposed to be) than making an in-flight phone call to Ban Ki-Moon.

I agree that it is good to capture this type of information in books,, but I'm not as big of a book reader as you. I can certainly agree with the last part of that statement!

Ultimately, I'm glad that NOVA allowed me to "go along on the ride" with the Solar Impulse team to get a better feel for what was involved in their incredible feat.

Reg, let me say that I agree that pushing the envelope as above can be valuable, but in this sort of thing, it's the scientific and technical problems that arise during the design and development stages, and the work which resolves them, that provide the value; the flight itself is just the culmination of all that. After all, most knowledge is gained by the errors and mistakes made along the way.

Aside from the claimed motivation for the flight, which IMO was pure PR B.S., my issue with this episode was the emphasis on the flight rather than what came before, where virtually all of the important stuff happened. My impression that the show broke down as roughly 5-10 minutes of technical info and issues, 15-20 minutes of travelogue and PR fluff, and the rest was occupied by the flight and ground periods between legs. Now, maybe my memory is faulty, but what I remember of the Nova episode on the Gossamer Condor (equally meaningless from any practical perspective at the time) is that most of that episode was taken up with the D&D period detailing the issues and solutions, with the (short) culminating flight occupying just a few minutes of the show. Here's one version of the design brief for that a/c:

Gossamer Condor Design Brief

Designer: Paul MacCready

Problem Statement: No human-powered aircraft has ever beendeveloped that could truly fly or win the KremerPrize.

Design Statement: Design, build, and test a controlled, sustainablehuman-powered aircraft that meets the criteria setforth by the Royal Aeronautical Society for theKremer prize.

Constraints:

1. Maximum 1/3 horsepower human engine output2. Unassisted take-off3. Able to ascend to a height of at least 10 feet4. Must fly a continuous distance of at least onemile around two pylons placed ½ mile apart5. Capable of making complete left and right turns6. After a full mile-long flight, must ascend again toa height of at least 10 feet

Nova is a science/technology show, so let's cover the science and technology - the Solar Impulse 2 flight itself was essentially boring (I'd guess that 90%+ was on autopilot), with about the only technical thing they learned during it being the need to provide venting for the sealed, insulated battery pack to deal with a wider range of temps. Obviously, there were no LEAF owners from hot climates on the development team! BTW, I had to take a short bathroom break during the show so maybe I missed it, but did they ever determine what was causing the A/P alarms? I never saw any explanation given.

So, out of 2 hours, let's have 1:30 or 1:40 on everything that led up to the flight including Solar Impulse 1, and then :20 or :30 covering the period of the flight itself. It's just as dramatic, and far more interesting to an audience curious about the science and tech. It would obviously have been more difficult to do this in this case than for the Gossamer Condor episode, given the much longer total time frame and the fact that most of the work took place in a foreign country rather than Mojave airport and other places in SoCal, but it could have been done. ISTR there was a fair amount of basically home movie footage included in the earlier show showing trials and problems, but the interest didn't suffer for that. Here's some: https://www.youtube.com/watch?v=l4wlC1Qex8A

40 years ago! Now I'm feeling old , and I'd forgotten that Paul MacCready was awarded the 1979 Collier Trophy for the concept, design and construction of the Gossamer Albatross (first human-powered flight crossing of the English Channel). As Solar Impulse 2 wasn't American it wouldn't be eligible.

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.